(a) Field of the Invention
The present invention relates to a method and apparatus for transmitting/receiving data using visible light communication. More particularly, the present invention relates to a method of transmitting data using light generating in a light emitting diode lighting device and of receiving data using an image sensor that senses light as an image.
(b) Description of the Related Art
Nowadays, as a lighting device using a light emitting diode (LED) as a light source is widely used, visible light communication (VLC) technology that can communicate with an LED lighting device has been introduced.
The VLC technology is communication technology that loads data at a visible light wavelength band of light in which a person can recognize with eyes and that transmits the data by wireless. Because the VLC technology uses a visible light wavelength band, the VLC technology can simultaneously perform lighting and communication and thus the VLC technology has a characteristic and a merit different from communication technology using a laser diode (LD) and communication technology of an infrared ray band and an ultraviolet ray (UV) band.
Visible light lighting in which a person can recognize can be variously used for an electric scoreboard, a sign board, a flat panel display back light unit (BLU), and an indoor/outdoor illuminating lamp. Lighting that is used in this way is disposed to correspond to a use purpose using one LED or a plurality of LEDs, and the use number thereof is determined.
The LED is used as lighting using a property that changes electricity to light. Communication using an LED lighting device sustains communication as well as basic lighting as the receiving side recognizes flickering of light of the transmission side. A lighting device in which a person uses should not have flickering for eye-safety, should sustain sufficient illumination Intensity according to a purpose, and should have a dimming function of sometimes adjusting brightness of light. Further, in order to use for communication, the lighting device should have a function of transmitting data by wireless.
FIG. 1 is a diagram illustrating a configuration of a conventional data communication apparatus using visible light communication.
Referring to FIG. 1, a transmitter 10 includes a controller 11, a modulation unit 12, a light source driver 13, and an array light source 14 including a plurality of LEDs that are coupled in series and in parallel, and a receiver 20 includes a photoelectric converter 21 including a photo diode or an image sensor, a demodulation unit 22, and a data processor 23.
The modulation unit 12 modulates transmission data that are input from the controller 11, and the light source driver 13 drives the array light source 14 and transmits data that are modulated in the modulation unit 12 through light that is emitted from the array light source 14.
Further, data that are transmitted through light are received in the photoelectric converter 21 of the receiver 20, are converted to an electrical signal, are demodulated in the demodulation unit 22, are restored to transmission data, and the data processor 23 processes transmission data to correspond to a corresponding application. In this case, technology that performs communication using a wavelength of light that is emitted from the array light source 14 as a visible light band becomes VLC technology.
When transmitting data, the transmitter 10 loads and transmits data by simultaneously quickly turning on/off a plurality of LEDs. That is, a set of a plurality of LEDs is transmitted as one light source. Therefore, a data amount to be transmitted is limited as an ability that can transmit from one array light source 14, which is an assembly of a plurality of LEDs and thus a limitation exists in increasing a transmission data amount.
Further, because the receiver 20 using an image sensor should identify data with a flicker of light within frames per second in a pixel range in which an image sensor can receive, data reception is limited to frames per second in which an image sensor can sense.
“Imaging device and method for reading signals from such device (U.S. Pat. No. 7,728,893 B2)”, which are a related art that is related to VLC relate to an apparatus that can simultaneously receive information of different ID beacons, if ID beacon light exists within a pixel position at which an image sensor can receive, when ID beacon light using LED lighting is transmitted from a plurality of different positions. In this case, because information in which each ID beacon generates is individual information, there is a drawback that a data receiving amount is limited to frames per second in which an image sensor can sense.
Further, as another related art, “two-dimensional barcode localization for camera based devices (Pub. No. US 2010/0084470 A1)” is a method of recognizing and decoding a two-dimensional barcode using a camera, and the two-dimensional barcode has a relatively more information amount than that of an one-dimensional barcode, but because the two-dimensional barcode has no function changing on a time zone basis, the two-dimensional barcode has a drawback that can read only a limited information amount.
As another related art, “LED display (Korean Patent Application Laid-open No. 10-2010-0013245) using an optical recognition pen” is technology that puts a barcode beside a display using an LED and in which an optical recognition pen device for recognizing the barcode recognizes the barcode, sends a control command by wireless, and changes display contents of the LED display. The technology changes contents of the LED display by assistance of an external system with fixed and limited barcode information and thus has a drawback that information can be acquired only when a communication function such as a network is mounted.